CAVERNOUS TRANSFORMATION OF THE PORTAL-VEIN - PATTERNS OF INTRAHEPATIC AND SPLANCHNIC COLLATERAL CIRCULATION DETECTED WITH DOPPLER SONOGRAPHY

OBJECTIVE. Cavernous transformation of the portal vein is defined as t he formation of venous channels within or around a previously thrombos ed portal vein. The purpose of this work was to study the hemodynamic consequences of cavernous transformation of the portal vein in a group of afflicted patients by use of Doppler sonography. We wished to stud y the evolution from portal vein thrombosis to the formation of cavern ous transformation, the extent of resulting extrahepatic collateral ch annels, and the patterns of splanchnic collateral circulation. MATERIA LS AND METHODS. Seventy-five patients (48 adults and 27 children) with cavernous transformation of the portal vein were studied with color a nd/or pulsed Doppler sonography. Blood flow in the extrahepatic portal vein, in its segmental branches, in the hepatic veins and artery, and in the splanchnic veins was examined. Collateral pathways were sought . For nine patients with acute thrombosis of the portal vein, serial e xaminations were performed during the formation of cavernous transform ation. RESULTS. In nine patients, a fresh thrombus filled and distende d the portal vein and became recanalized within a few days. Tortuous v essel appeared at the porta hepatis. These were characterized as veins or arteries with Doppler sonography. Soon the portal vein could no lo nger be identified within the mass of tortuous vessels. The cavernous transformation developed within 6-20 days of the acute thrombosis. A s pongelike mass of collateral vessels around the main portal vein was s een in all but two patients. Intrahepatic extension of the cavernous t ransformation was seen in 57 patients (76%) and involved one or more i ntrahepatic portal veins. Two types of collateral circulation were obs erved: portosystemic, mainly through the left gastric and the perisple nic veins (the caput medusae, i.e., the paraumbilical-to-abdominal ven ous route, was never seen); and portoportal, from the periportal or pe richolecystic venous channel to the intrahepatic portal veins. In nine patients, flow within unaffected intrahepatic branches of the portal vein was reversed and directed toward the cavernous transformation sur rounding other, thrombosed intrahepatic segments of the portal vein. C ONCLUSION. After thrombosis of the portal vein, portoportal venous cha nnels may form not only at the porta hepatis but also within the liver . Intrahepatic blood may be shunted from one segmental portal vein to another. In addition, portosystemic collateral channels are formed, su ggesting that, despite extensive hemodynamic adaptations, portal hyper tension ensues.